[Cfrg] readability suggestion about rfc8032 section 5.2, table 2

Michael Richardson <mcr+ietf@sandelman.ca> Tue, 31 January 2017 17:11 UTC

Return-Path: <mcr+ietf@sandelman.ca>
X-Original-To: cfrg@ietfa.amsl.com
Delivered-To: cfrg@ietfa.amsl.com
Received: from localhost (localhost []) by ietfa.amsl.com (Postfix) with ESMTP id F0F56129FF5 for <cfrg@ietfa.amsl.com>; Tue, 31 Jan 2017 09:11:41 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -5.1
X-Spam-Status: No, score=-5.1 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, RP_MATCHES_RCVD=-3.199, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([]) by localhost (ietfa.amsl.com []) (amavisd-new, port 10024) with ESMTP id BZ5EyfoyBYrH for <cfrg@ietfa.amsl.com>; Tue, 31 Jan 2017 09:11:40 -0800 (PST)
Received: from tuna.sandelman.ca (tuna.sandelman.ca []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id C4D21129FF2 for <cfrg@irtf.org>; Tue, 31 Jan 2017 09:11:40 -0800 (PST)
Received: from sandelman.ca (obiwan.sandelman.ca [IPv6:2607:f0b0:f:2::247]) by tuna.sandelman.ca (Postfix) with ESMTP id D40C12009E; Tue, 31 Jan 2017 12:32:17 -0500 (EST)
Received: from obiwan.sandelman.ca (localhost [IPv6:::1]) by sandelman.ca (Postfix) with ESMTP id E09CE6381A; Tue, 31 Jan 2017 12:11:39 -0500 (EST)
From: Michael Richardson <mcr+ietf@sandelman.ca>
To: cfrg@irtf.org
X-Attribution: mcr
X-Mailer: MH-E 8.6; nmh 1.6+dev; GNU Emacs 24.5.1
X-Face: $\n1pF)h^`}$H>Hk{L"x@)JS7<%Az}5RyS@k9X%29-lHB$Ti.V>2bi.~ehC0; <'$9xN5Ub# z!G,p`nR&p7Fz@^UXIn156S8.~^@MJ*mMsD7=QFeq%AL4m<nPbLgmtKK-5dC@#:k
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="=-=-="; micalg="pgp-sha256"; protocol="application/pgp-signature"
Date: Tue, 31 Jan 2017 12:11:39 -0500
Message-ID: <19607.1485882699@obiwan.sandelman.ca>
Archived-At: <https://mailarchive.ietf.org/arch/msg/cfrg/V41eGD5LE4Yb2Ut6qX19hx5TTIA>
Cc: draft-irtf-cfrg-eddsa@ietf.org
Subject: [Cfrg] readability suggestion about rfc8032 section 5.2, table 2
X-BeenThere: cfrg@irtf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: Crypto Forum Research Group <cfrg.irtf.org>
List-Unsubscribe: <https://www.irtf.org/mailman/options/cfrg>, <mailto:cfrg-request@irtf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/cfrg/>
List-Post: <mailto:cfrg@irtf.org>
List-Help: <mailto:cfrg-request@irtf.org?subject=help>
List-Subscribe: <https://www.irtf.org/mailman/listinfo/cfrg>, <mailto:cfrg-request@irtf.org?subject=subscribe>
X-List-Received-Date: Tue, 31 Jan 2017 17:11:42 -0000

Should we do a bis, this is a readability suggestion.  Maybe there
was a flame war over this already, if so, I appologize :-)

{And, I can't tell you how happy I am to have 8032 out. Thank you thank you
thank you!!!!!}

It says:

   |   PH(x)   | x (i.e., the identity function)                       |

                       Table 2: Parameters of Ed448

   Ed448ph is the same but with PH being SHAKE256(x, 64) and phflag
   being 1, i.e., the input is hashed before signing with Ed448 with a
   hash constant modified.

It really took me awhile to tweak into the "ph" in the "Ed448ph" in that
sentence.  It sure looked like an errata in the table.  As if there
was a copy and paste error from Ed25519, and that 448 and 25519 should
differ by PH(x) as well.

I think that the presentation would work better if the B and L value were
removed from the table and presented inline. (It would also be easier to
copy and paste into code, or be extracted via xmlpath).  With those
values removed from the table, it would be much more readable, and I
would suggest that it have three columns, one for Ed448 and one for Ed448ph.

Similarily for the Ed25519/Ed25519ph/Ed22519ctx table, which could then
have four columns.

I also suggest that the point addition examples in 5.1.4 not repeat any
of the variables used in the tables, specifically, "B" :-)

Please let me know if this is sufficiently important to enter an errata.

Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-